Oxyalkylation of solid polyols



United States atent O OXYALKYLATION F SOLID POLYOLS Arthur W. Anderson, Midland, Mich., assignor to The Dow Chemical Company, Midland, Mich., a corporation of Delaware No Drawing; Application May 9, 1957 Seri'alNo. 658,020

14 Claims- (Cl. 260-9209) This invention relatesytq processes for the oxyalkylat of gh-m ltin pe yhyd q y c mpo n The conventional processes for the oxyalkylation of solids involve either fusing the solid or dissolving it in a suitable solvent. Heat-sensitive compounds having relatively highmelt-ing points, such as sugars and pentaerythritol, are damaged and discolored by being heated at their melting points. Theme of; solvents is objectionable because of the added expense of a solvent recovery system. In some cases the alkylene oxide used as a reactant can also serve as a solvent but in most cases the polyol is substantially; insoluble in; alkylene oxides. In fact, no practical solvent is known. that will simultaneously dissolve these polyols, the alkylene oxides and the conventional caustic alkali catalystswithout entering into reaction with the oxide, Because. of these difliculties, no practical process has hitherto been available: for the oxyalltylation of highmelting polyols that are substantially insoluble in alkylene oxides without. the. simultaneous formation of lay-products.

An object of this invention is to: provide processes for the oxyalkylation. of high-melting polyols at temperatures substantially below the meltingpoints. of the polyols and in. the absence of a solvent other than the. alkylene oxide reactant, whereby at least one. mole. of alkylene oxide reacts with each. hydroxylgroup of the polyol and liquid products are formed. Another object is. to provide liquid oxyalkylatedx derivatives; of. highemelting polyols free of inorganic impurities, substantially free of; any organic byproducts, and of discoloration and; decomposition products formed when the polyols are heated; above the temperature range inwhich theyare; stable.

According; to. the; invention, high-meltin heat-sensitive. polyols thatare, substantially insoluble in alkylene oxides are oxyalkylated at temperatures below their melting pointsand decomposition temperatures and in the absence; Of solventhy the use of trirnethylamine as a catalyst. It has been diseoveredrthat trimethylarnine not only catalyzes the reaction of alkylene oxides with hydroxyl compounds. but it alsosol-uatesor otherwise activates solid polyols so that they readily react with alkylene oxides at. temperatures as low as 80- C.

I have observed that other lower. alkyl tertiary amines, specifically trietliylandtripropyljamine, have a somewhat similar catalytic effect 'in that they elf'ectively catalyze. the

reaction of propylene oxide with polyols. In such reactions, however,these particular amines produce a peculiar efiiect; namely, they catalyze the reaction of one, and only one mole of propylene oxide with each hydroxyl group of the polyol. Such an effect has not been observed with other catalysts, including trimethylarnine, or other alkylene oxides. This particular discovery is disclosed and claimed in my copending application entitled Hydroxypropylation of Hydroxy Compounds, filed December 24, 1956, Serial No. 630,067.

The term high-melting heat-sensitive polyol as used herein means solid compounds which contain at least 4 alcoholic hydroxyl groups, which melt above about without precautions to exclude air or light. Commercially important examples of polyols included in the invention include the heat-sensitive sugars, suchas sucrose; polymethylolsgsuch' as pentaerythritol, dipentacrythritol and tripentaerythritol and the like and mixtures of any of the above materials.

The alkylene oxides useful in the invention are the vicinal oxides; that is, those which the oxide oxygen atom (oxirane oxygen). is attached to two adjacent aliphatic carbon atoms. The alkylene group of the alkylene oxide may bear a phenyl group as a substituent. Suitable oxides include ethylene oxide, 1,2-propylene oxide, 1,2- and 2,3-butylene oxides, isobutylene oxide, butadiene monoxide, styrene oxide, and the like and mixtures thereof.

The amount oftrim'ethylamine used as catalyst is not cri-t ieal. As little asa few hundredths of onepercer t, based onpolyol, is frequently effective, though itis usually preferred to use at least about 0.1 percent. On the other hand, there is no advantage in using amounts greater than about 5' percent. The preferred range is about 0.1 to 2 percent, depending somewhat on the reactivity of the oxide, the reaction temperature, and the polyol used.

In general: it is preferred to conduct the reaction at the lowestpractical temperature, it being recognized; that longer reaction times are required at lower temperatures. When a highly reactive oxide, such as ethylene oxide, is

i being used,. a satisfactory rate of reaction frequently can ing oxide: at abouttherate attwhich it reacts, thus permitting a steady rate. of. reaction. and effective temperature control;

As is usual in oxyalkylation processes; it is desirable to exclude water and oxygen. during the reaction period and to, usereagents free of moistm e aldehydes and other interfering substances.

The practice ofthe invention is illustrated by'the following examples:

Example 1..-?0gcypr0pyla'ti0n of sucrose A pressure reactor was loaded with 2400. grams of sucrose, 3600 grams of propylene: oxide and 21 grams of trimethylamine. It was then closed, flushed with nitrogen, and heated to C. with constant stirring. A very vigorous reaction then began which required effective cooling to control the temperature.

After 2.25 hours the reaction substantially ceased, the pressure being zero (gauge). The product was a sirupy, watersoluble liquid. Based on the yield of 5925 grams, it contained 8.66 oxypropylene groups per sucrose molecule.

Example 2.-Oxypropylation of sucrose When the procedure of Example 1 was: repeated except that a 10:1 molar ratio of propylene oxide to sucrose and a temperature of 8090 C. were used, substantially all the oxide reacted in 10 hours and the sirupy product was estimated to contain 9.5 oxypropylene groups per sucrose molecule.

Example 3.xybutylation of pentaerythritol dropped from a maximum of 43 p.s.i.g. to 9 p.s.i.g.

The unreacted butylene oxide was removed by appli 'cation of vacuum, thus leaving the product as a sirupy,

amber liquid, substantially insoluble in water and containing 5.06 oxybutylene groups per pentaerythritol molecule.

Dipentaerythritol and tripentaerythritol, corresponding to the formula wherein n is 2 or 3, may be substituted for pentaerythritol in the above example with substantially equivalent results.

Example 4.-Oxyphenethylation of sucrose A pressure reactor was charged with 342 grams (1 mole) of sucrose, 960 grams (8 moles) of styrene oxide and 13 grams of trimethylamine. It was then heated for 1.9 hours at 118-122 C. and for 8.6 hours at 147- 151 C.

After being vacuum stripped of volatiles, a brown viscous liquid product remained which contained an average of 9.5 oxyphenethyl groups per sucrose molecule.

Example 5.Oxyethylati0n of sucrose In a suitable reactor, 1368 grams (4 moles) of sucrose, 14.9 grams of trimethylamine and 300 grams of ethylene oxide were heated to 100 C. The exothermic reaction raised the temperature to 133 and the pressure to 155 p.s.i.g. Thereafter the temperature was maintained at 90-105 and ethylene oxide was added at a rate sulficient to maintain the pressure at 3075 p.s.i.g. When a total of about 900 grams of ethylene oxide had been added, the reactor was cooled, evacuated to remove volatiles, and emptied. The product was a very viscous brown sirup containing 20.25 oxyethylene groups per sucrose molecule.

Example 6 A 1263 gram portion of the product of Example was returned to the reactor. Four grams of trimethylamine were added, the temperature was raised to 110130 and the addition of ethylene oxide was continued until a product containing 81 oxyethylene groups per sucrose molecule was obtained. It was a water-miscible brown sirup which unexpectedly had much lower viscosity than did the product of Example 5.

The ethers of the invention are generally useful as thickeners and hydraulic fluids and as softeners and plasticizers for paper, cellophane and cellulose-based plastics. They are particularly useful as intermediates, since they may be incorporated into alkyd or polyurethane resins or they may be esterified with fatty acids or etherified with polyoxyalkylene glycols to form detergents, emulsifying agents, wetting agents, antifoamers and related surfactants.

I claim:

1. A process for oxyalkylating a high-melting heatsensitive polyol comprising contacting the polyol containing 4 to 8 hydroxyl groups per molecule with at least a stoichiometric amount, based on the hydroxyl content of the polyol, of at least one vicinal alkylene oxide in the presence of a catalytic amount of trimethylamine and at a temperature above about C. but below the normal melting point of the polyol, whereby substantially each hydroxyl group of the polyol is oxyalkylated and a liquid polyoxyalkylene ether is produced. v

2. A process as defined in claim 1 wherein the polyol is a sugar.

3. A process as defined in claim 2 wherein the sugar is a disaccharide.

4. A process as defined in claim 3 wherein the disaccharide is sucrose.

5. A process as defined in claim 1 wherein the polyol has the formula wherein n is an integer from 1 to 3.

6. A process as defined in claim 5 wherein the polyol is pentaerythritol.

7. A process as defined in claim 6 wherein the polyol is diapentaerythritol.

8. A process as defined in claim 1 wherein the alkylene oxide is ethylene oxide.

9. A process as defined in claim 1 wherein the alkylene oxide is propylene oxide.

10. A process as defined in claim 1 wherein the alkylene oxide is a butylene oxide.

11. A process as defined in claim 1 wherein the alkylene oxide is 1,2-butylene oxide.

12. A process as defined in claim 1 wherein the alkylene oxide is 2,3-butylene oxide.

13. A process as defined in claim 1 wherein the alkylene oxide is styrene oxide.

14. A process for oxyethylating sucrose comprising contacting solid sucrose with at least 8 molar equivalents of ethylene oxide in the presence of a catalytic amount of trimethylamine at a temperature of about 80 to C. and a pressure suflicient to maintain the ethylene oxide in the liquid state until substantially every hydroxyl group of the sucrose has been oxyalkylated.

References Cited in the file of this patent UNITED STATES PATENTS Kerr et a1. a Jan. 31, 1956 

14. A PROCESS FOR OXYETHYLATING SUCROSE COMPRISING CONTACTING SOLID SUCROSE WITH AT LEAST 8 MOLAR EQUIVALENTS OF ETHYLENE OXIDE IN THE PRESENCE OF A CATALYTIC AMOUNT OF TRIMETHYLAMINE AT A TEMPERATURE OF ABOUT 80 TO 150* C. AND A PRESSURE SUFFICIENT TO MAINTAIN THE ETHYLENE OXIDE IN THE LIQUID UNTIL SUBSTANTIALLY EVERY HYDROXYL GROUP OF THE SUCROSE HAS BEEN OXYALKYLATED. 